In a charging apparatus for a resist liquid, a filter is arranged in a liquid passage to capture impurities contained in the resist liquid (for example, refer to Patent Document 1 or 2). In a photoresist coating device that is disclosed in Patent Document 1, “in a supplying pipe arrangement 2, which starts from a photoresist gallon bottle 21 to a three-way valve 13, a pump 3, a filter unit 4, a three-way valve 14 and reaching an application nozzle 5, a circulating pipe arrangement 8 is provided, which directly returns from the three-way valve 14 to the three-way valve 13”. In the above device, “when the coating is suspended, the photoresist is prevented from stagnating by circulating the photoresist through a cyclic line starting from the three-way valve 13 to the pump 3, the filter unit 4, the three-way valve 14 and the circulating pipe arrangement 8, and returning to the three-way valve 13”.
Moreover, Patent Document 2 discloses a method of manufacturing a photoresist composition with a reduced particulate amount, in which a photoresist composition is passed through a filter, the passed photoresist composition is further led to the filter, and is circulated in a closed system, thereby removing fine particles in the photoresist composition. In the above method, by passing the photoresist composition through the filter before charging thereof, impurities in the photoresist composition are removed.
Patent Document 1: Japanese Unexamined Patent Application No. H10-172881
Patent Document 2: Japanese Unexamined Patent Publication No. 2002-62667